How to Grow and Care for Bear’s Breeches

Bear’s Breeches, known botanically as Acanthus mollis, brings drama and structure to the garden with its large, glossy, and deeply lobed leaves that form a substantial mound of foliage. From this base, tall flower spikes emerge in the summer, displaying white petals beneath hood-like purple bracts. The distinctive shape of its leaves has been admired for centuries, famously serving as the inspiration for the carved details on Corinthian columns in classical Greek art.

Ideal Growing Conditions

Light

The amount of sun Bear’s Breeches requires is adaptable. In cooler summer climates, it can thrive in full sun, but in hotter regions, a location with partial or dappled shade is more suitable to prevent scorching. Providing at least a few hours of sun daily is important for encouraging good flower production, as too much shade may result in fewer blooms even if the foliage remains lush.

Soil

This plant prefers rich, fertile soil that is consistently moist but also well-drained. Amending the planting area with compost or other organic matter will help create this environment. Good drainage is particularly important during the winter months, because if the roots sit in cold, wet soil for extended periods, they can be susceptible to rot. Established plants can become more tolerant of poorer soil, but starting them in an ideal medium is best.

Water

During its active growing season in spring and summer, Bear’s Breeches benefits from regular watering, aiming for about one inch of water per week once established. This consistent moisture helps support its large leaves. After the plant has matured and developed a deep root system, it becomes quite drought-tolerant.

Temperature and Humidity

Bear’s Breeches is a hardy perennial suitable for USDA zones 7 through 10 and can tolerate a range of humidity levels. In colder regions at the edge of its hardiness range, providing a thick layer of mulch in late fall can help protect the roots from frost. In areas with mild winters, the foliage may remain evergreen, adding interest to the garden year-round.

Fertilizer

This plant is not a heavy feeder, so a single application of well-rotted manure or compost in the spring is often sufficient for the season. Alternatively, a balanced, slow-release fertilizer can be applied at the beginning of the growing season.

Managing Growth and Pruning

Bear’s Breeches is known for its vigorous growth and ability to spread, requiring some management. The plant expands via a deep root system, and since any small piece of root left in the ground can sprout, it can be difficult to move or eradicate once established. To prevent its spread into surrounding garden beds, installing an underground root barrier at the time of planting is an effective strategy.

Pruning is straightforward and serves to maintain the plant’s appearance. After the blooms have faded in mid-to-late summer, cut the flower stalks back to the base to tidy the plant and encourage a flush of fresh foliage. Throughout the growing season, any foliage that becomes dead or damaged can be trimmed away. A more significant tidying can be done in the spring before new growth emerges.

How to Propagate Bear’s Breeches

One propagation technique is division, which is best performed in the spring or autumn. This involves carefully digging up a mature, congested clump and using a sharp spade to separate the root ball into smaller sections. Each new division should have a healthy portion of roots and foliage before being replanted.

Another method is taking root cuttings in the spring, which is often easier than lifting the entire plant. By carefully excavating around the base of an established plant, you can expose some of the thick, fleshy roots. A section of root can be cut and then potted in compost to grow on before being planted out in the garden.

Common Pests and Diseases

The most common pests are slugs and snails, which are drawn to the plant’s large, succulent leaves. These pests create holes and ragged edges on the foliage, and their presence can be confirmed by the silvery slime trails they leave behind. Management can include using slug baits or creating barriers with coarse materials around the base of the plant.

The most frequent disease is powdery mildew. This fungal issue appears as a white, dusty coating on the leaves, typically in humid conditions with poor air circulation. While unsightly, it is not usually a serious threat to the plant’s health. Improving air circulation by properly spacing plants and applying a fungicide, if necessary, can help manage the problem.